Cloud

"What are you researching?" Hesta asked.

Ksenia smiled and pointed at the sky. "Clouds."

The rain grew heavier.

Hesta followed behind Ksenia, and the rain soaked them both through. They moved slowly through the woods, Ksenia liable to stop at any moment—a line of ants by the path, a round sparrow drenched in the rain, or a cluster of oddly colored flowers could all make her pause. Whenever they came across some fleeting sight, she would pull Hesta to her side to look with her.

Whenever the two held their breath and stared at something, heaven and earth seemed to fall silent.

"Ksenia."

"Mm?"

"Tell me more about your research," Hesta said softly. "What do you study about clouds?"

"How clouds form," Ksenia replied.

Hesta looked a little puzzled. "Humanity still hasn't figured that out?"

Ksenia laughed. "What do you think the answer is?"

"...Water on the ground, water on the sea, evaporates into the air?"

"That's right, broadly speaking," Ksenia said with a nod. "But simply knowing that answer is meaningless. The more important questions are: under what meteorological conditions does water vapor form what kinds of clouds? What conditions produce rainfall? What effects do different atmospheric pollutants have on the formation of clouds? ...At present, humanity's understanding of the properties of clouds is still insufficient. There are many questions like this that seem simple but haven't actually been figured out.

"My current experiment uses aircraft to take cross-sections of massive cloud layers in the sky. The pilot flies the plane into the clouds, passing through each altitude one by one. On the one hand, this lets us directly observe all kinds of phenomena within the cloud layer; on the other, the various instruments mounted on the aircraft collect the temperature, humidity, wind speed, droplet size distribution, and so